Livestock production today is no longer limited to obtaining economic goals. Modern society is concerned about food safety and quality, efficient and sustainable animal farming, healthy animals, guaranteed animal wellbeing and acceptable environmental impact of livestock production. As a consequence, there is a growing need to monitor many variables during the entire production process in order to satisfy these targets. In the past, livestock management decisions have been based almost entirely on the observation, judgment and experience of the farmer. Frost, et al. (1997) Computers and Electronics in Agriculture 17: 139-159. However, the combination of the increasing scale of the farms and the corresponding high number of animals, has resulted in an increasing administrative, technical, organizational and logistic workload for the farmer and increased the difficulty in monitoring the animals. Berckermans (2004) “Automatic On-Line Monitoring of Animals by Precision Livestock Farming.” International Society for Animal Hygiene, pages 27-30.
Modern, intensive farms make the farmer totally responsible for all livestock under the farmer's control. Over the last three decades farming practice has moved away from self-sustaining mixed livestock enterprises with relatively small numbers of several species, towards large, single species units. Animals now are produced intensively, and maintained under near ideal conditions for growth and production within current technological limits. The majority of animals are constrained within a building or stockyard for most or all of their lives. As they are prevented from foraging for their own food, the farmer takes complete responsibility for all aspects of their husbandry. Monitoring of feeding, environment, reproduction, health, growth, marketing, transport and quality becomes the responsibility of the farmer. This responsibility is not only moral; it is also in the farmer's commercial interest to satisfy these basic needs of their livestock. Frost, et al. (1997) Computers and Electronics in Agriculture 17: 139-159.
The main purpose of most livestock production enterprises is to satisfy the demands of a customer by providing a product which meets the customer's requirements at a price which enables the producer to make a profit. The customer's requirements are becoming increasingly well defined. An example is the meat industry which pays producers more for animals of a particular weight, conformation and composition. Another example is the dairy industry which pays dairy farmers according to milk quality and composition.
Sensors can be used to gather an increasingly wide range of information. However with the development of these sensors it becomes more important to develop systems which can collect, process, and utilise the information. Raw data, on its own, is of limited value. The farmer can maximise the efficiency of a production system only by monitoring all its critical stages and targets and ensuring that they are kept close to the optimum. For example, it may be necessary to assimilate data on the climate within and without a building, the breed, number, age, feed level and weight of animals, their growth rate, activity and health records and market requirements.
Animal Weight
The weight of an animal is an important indicator of the wellbeing and value of an animal. However very few livestock producers weigh their animals frequently. This is often due to the lack of convenient weighing equipment. Hog farmers, cattle farmers, and poultry farmers need to pay close attention to the weight of the animal in order to be profitable. Growing hogs or cattle beyond their slaughter weight or market weight dramatically reduces their market value, causing the farmers to lose significant revenue. Most farms have a single weighing scale that is used when it is decided that animals are ready for market, by which time quite a few could be over the weight threshold.
For poultry, an automatic broiler weighing system is described by Turner, et al. (1984) J. Agric. Eng. Res. 29: 17-24. This consists of a perch for individual birds, suspended on a strain gauge link. The perch is monitored by a computer which tares the weight between each record, stores and processes each reading to eliminate false data, and provides the farmer with a weight distribution for the flock. An abnormal change in the weight of the birds can provide an early warning of health problems, or of problems with feeding or ventilation equipment. A further enhancement allows the birds in the flock to be split into separate groups according to weight, by automatically directing them to a ‘heavy’ or a ‘light’ pen as they leave the weigher. A difficulty with any system that operates on a sample of the population is ensuring that the sample is representative of the population.
Knowledge of the growth rate of pigs provides valuable information on health, productivity and yield. A growth rate curve for example shows up deviations from the ideal, indicating checks in growth which require investigation, or delays in starting growing following weaning. In order to gain enough readings to be able to follow the growth rate of individual pigs, it is necessary to weigh them at least weekly. This is impractical if done conventionally, due to the large labour input it requires, and the stress it causes to man and animal. If pigs were weighed automatically and frequently, each time they attended a feeder for instance, then it would be possible to produce a growth curve, provided that each animal was identified using electronic tags, for example. Load platforms are available for weighing pigs attending feed stations, but have been found to be unreliable due to mechanical interference by the pigs and dirt building up under the platform. Turner, et al. (1985) Automatic weight monitoring pigs—Part 1: Trials of prototype weight platforms. Silsoe Research Institute Divisional Note DN/1266, Silsoe Research Institute, Silsoe, Bedford, UK.
It has been found that there is a strong correlation between the weight of a pig and its plan view area. Schofield (1990) J. Agric. Eng. Res. 47: 287-296. This has led to the development of systems in which images from a video camera, suspended over a pig, are analysed to extract the plan view area and estimate the weight of the animal. Schofield & Marchant (1991) Proc. Int. Soc. Optical Eng. 1379: 209-219. Pig weights have been determined to within 5% accuracy by this method. Schofield (1993) In: Proceedings of the 4th livestock environment symposium, Warwick, England, ASAE, pages 503-510; Minagawa, et al. (1993) Proc. 4th Livestock Environment Symp., Warwick, England, ASAE, pages 528-535. This type of system has the advantages of not interfering with the animal or requiring equipment to be installed at pig level where it is vulnerable to attack. It also has no moving parts which should benefit reliability. Disadvantages are that the performance of the system depends on the quality of the images, which can be affected by lighting conditions, and that the relationship between weight and plan view area has to be established for each different breed of pig; it is not yet known how many relationships will be required to cover all breeds of pig that are currently being grown.
An automatic weighing machine for cows has been reported. Filby, et al. (1979) J. Agric. Eng. Res. 24: 67-78; Laycock & Street (1984) J. Agric. Eng. Res. 30: 265-273. The automatic weighting machine for cows consists of a load cell connected to a platform across which cows walked as they left the milking parlour. One of the main difficulties was that of filtering the highly variable signal that was produced as the cow walked across the platform. It was also necessary to ensure that weights were recorded only when a single cow had all of its weight on the platform, and that spurious readings due to more than one cow at a time being on the platform, or a cow not having all of its feet on the platform, were rejected. In practice it was found that about 80% of a herd of 270 cows could be weighed on exit from a conventional 16 place herringbone parlour, which meant that weekly mean weights for about 90% of the herd could be obtained. The error associated with each weight was found to be greater than that from a manual weighing but it was estimated that the accuracy of a mean weekly weight of an animal measured by such a system was equal to that which would result from three manual weighings per week. This type of device has not been widely adopted, probably because of the technical problems mentioned above, and because the economic justification for weighing dairy cows frequently has not been established to the satisfaction of the farmer. Frost, et al. (1997) Computers and Electronics in Agriculture 17: 139-159.
Further, systems for estimating animal weight are described in the art. Mulder describes monitoring the condition of animals which utilizes current height and weight measurements taken from an animal in order to automatically derive a height-to-weight ratio. WO 2010/012433 and U.S. Patent Application Publication No. 2011/0125062. Also an automatic animal feed consumption monitoring system comprising an enclosing having a quantity of feed therein is described by Travis were the sensor detects an animal's entry into a stall and records the entry time, the food weight at the beginning of the feeding and the animal's exit time and food weight at the end of the feeding. U.S. Patent Application No. 2007/0137584. The disadvantage of these systems is that they only approximate the weight and health of the animal but are limited to a single location and may require that the animal be corralled or trained to use the device.
Thus a need exists in the art for an efficient remote method and system for monitoring farm animal weight.